Familial DNA Searching for Criminal Forensics: Q&A

When DNA evidence is collected at a crime scene, submitting the sample for a search within a DNA database does not always identify a profile match. There is a way to extend that search and generate leads, called familial searching (FS). FS is used to identify close biological relatives of an unidentified DNA profile obtained as evidence. The basic premise is that DNA profiles of immediate family members, such as siblings, parents, or children, are likely to have more alleles in common than unrelated individuals. These familial profile matches can generate new investigative leads for law enforcement.

Currently, a few states are using FS under their state database laws, although none explicitly permit FS. Many agencies have yet to adopt policies related to FS, even though it has been found to be as effective as CODIS for identifying sources of evidence. The absence of clear ethical guidelines and policy regarding how to properly utilize FS prevents many local and state jurisdictions from adopting this investigational tool.

In order to address concerns and existing policies related to FS and to guide policy decisions by agencies implementing FS, the National Institute of Justice (NIJ) issued the report Familial DNA Searching: Current Approaches in January 2015. The goal of the report was to provide information to policy makers, law enforcement officials, forensic laboratory practitioners, and legal professionals about how FS is being applied within the criminal justice realm.

Mr. Rock Harmon, former prosecutor

Mr. Rockne Harmon, former prosecutor

 

Answers to the following questions about FS were provided by Mr. Rockne Harmon, a retired former prosecutor and member of the team that produced the report for the National Institute of Justice.

 

What is familial DNA searching?

Familial searching (FS) is an additional search of a DNA profile in a law enforcement DNA database that is conducted after a routine search fails to identify any profile matches. The FS process attempts to provide investigative leads to agencies engaged in the pursuit of justice by identifying a close biological relative of the source of the unknown forensic profile obtained from crime scene evidence. Continue reading

Rapid DNA Technology: Establishing your Identity in Less than Two Hours

DNA SequenceWhile the forensic and general communities continue to argue about the merits of the recent Supreme Court ruling on collection of samples from arrestees prior to conviction, I am fascinated by the technology that make this question relevant. The conventional way of generating a DNA profile from a sample by STR (short tandem repeat) analysis is a long process involving a series of steps that require sophisticated expensive equipment, trained personnel and, more importantly, time. The actual process of DNA analysis consists of a) sample collection, b) DNA extraction, c) PCR amplification using 16 or more unique fluorescently labeled primer sets d) capillary electrophoresis to size labeled DNA amplicons, e) software analysis to size DNA fragments and allele calls based on migration of allelic ladder fragments, and f) comparison to known profiles in the database. This entire workflow can typically take days or even weeks, and therefore it is not surprising that we see newspaper reports of backlogs of criminal and other property cases. With these time ranges, the sample collected at a site would be of no practical use to most ongoing investigations. Continue reading